Cellular proliferative disorders such as cancer are among the most common causes of death in developed countries. For diseases for which treatments exist, such as cancer, despite continuing advances, currently used treatments exhibit undesirable side effects and limited efficacy. Identifying new effective drugs for cellular proliferative disorders, including cancer, is a continuing focus of medical research.
Obesity is an established risk factor for the development of approximately 30 different diseases and disorders, including cardiovascular and inflammation diseases, and cancer. Obesity has been identified as a risk factor for postmenopausal breast cancer and excess fat tissue (especially abdominal) has been associated with worse response to chemotherapy and shorter disease-free survival, regardless of menopausal status. Schaffler, A., Scholmerich, J., Buechler, C. (2007) Nat Clin Pract Endocrinol Metab 3:345-54; Vona-Davis, L. Rose, D P. (2007) Endocr Relat Cancer 14:189-206. While several adipose tissue-derived factors (e.g. estrogens, fatty acids, insulin-like growth factors, IL-6) have been proposed as possible mediators of the obesity-breast cancer link, recent data emphasize the roles of two adipokines: leptin and adiponectin. Cleary, M P., Ray, A., Rogozina, O P., Dogan, S., Grossmann, M E. (2009) Front Biosci (School Ed) 1:329-57. Cleary, M P., Grossman, M E. Ray, A. (2010) Vet Pathol 47:202-13. Although the molecular basis of this link is yet to be elucidated, recent studies have suggested that detrimental effects of obesity are mediated by fat tissue-derived adipokines, such as leptin, which is elevated in overweight people.
Adiponectin is a cytokine synthesized in and secreted by adipocytes. Adiponectin is elevated in lean individuals and low in obese people. Adiponectin is known to be a beneficial hormone, with clear catabolic effects on a number of metabolic processes, including glucose regulation and fatty acid metabolism. In addition, adiponectin has been shown to be a potent negative regulator of cancer cell growth and might play a preventive role against cancer development. Adiponectin is found in human serum at concentrations of 2-20 μg/ml. Grossmann, M E., Nkhata, K J., Mizuno, N K., Ray, A., Cleary, M P. (2008) Br J Cancer 98:370-9. Circulating adiponectin levels are inversely correlated with body mass index (BMI); in contrast, serum leptin positively correlates with BMI. Ryan, A S., Berman, D M., Nicklas, B J., Sinha, M., Gingerich, R L., Meneilly, G S, et al. (2003) Diabetes Care 26:2383-8. Wauters, M., Considine, R V., Van Gaal, L F. (2000) Eur J Endocrinol 143:293-311. Adiponectin levels are reduced in conditions of insulin resistance and cardiovascular disease, and even appear to precede these disorders. Yamamoto, Y., Hiroshe, H., Saito, I., Nishikai, K., Saruta, T. (2004) J Clin Endocrinol Metab 89:87-90. Furthermore, high circulating adiponectin levels correlate with reduced cancer risk, while low levels of the cytokine are associated with the presence of cancer. Barb, D., Williams C J., Neuwirth, A K., Mantzoros, C S. (2007) Am J Clin Nutr 86:s858-66. In general, adiponectin is considered a protective hormone: it exerts anti-diabetic, anti-inflammatory and anti-cancer effects. Adiponectin circulates in trimeric, hexameric, and higher order complexes. Fang, X., Sweeney, G. (2006) Biochem Soc Trans 34:798-801. The C-terminal half of the protein representing the globular domain exhibits potent metabolic effects in various tissues. Tomas, E., Tsao, T S., Saha, A K., Murrey, H E., Zhang, C C., Itani, S I., et al. (2002) Proc Natl Acad Sci USA 99:16309-13.
Two adiponectin receptors have been identified, AdipoR1 and AdipoR2. Yamauchi, T., Kamon, J., Ito, Y., Tsuchida, A., Yokomizo, T., Kita, S. et al. (2003) Nature 423:762-9. AdipoR1 is a high-affinity receptor for globular adiponectin and a low affinity receptor for the full-sized ligand. Wang, H., Zhang, H., Jia, Z. Craig, R. Wang, X., Elbein, S. C. (2004) Diabetes 53:2132-6. Both adiponectin receptors are 7-channel integral membrane proteins containing the N-terminal intracellular portion and the C-terminal extracellular portion (an orientation that is exactly the opposite of other G-protein coupled receptors). T-cadherin, a unique cadherin molecule, has been characterized as a third adiponectin receptor on vascular endothelial cells and smooth muscle. However, T-cadherin is just a co-receptor—it does not appear to play a role in direct ligand binding. AdipoR1 has 4 very short extracellular domains, 13, 6, 11 and 16 residues, respectively.
Adiponectin has a stimulatory effect on the phosphorylation and subsequent inactivation of 5′-AMP-activated protein kinase (AMPK), and on acetyl coenzyme A carboxylase (ACC), which is the downstream substrate of AMPK. Yamauchi et al. (2002) Nature Medicine 8:1288-95. In addition, adiponectin can stimulate extracellular-signal-regulated kinases 1 and 2 (ERK1/2), and activate peroxisome proliferator-activated receptor-α (PPARα) and stress responsive c-Jun N-terminal kinase (JNK). Yamauchi et al. (2003) J Biol Chem 278:2461-8. Adiponectin has also been shown to inhibit gene expression regulated by two essential transcription factors involved in growth and inflammation, respectively: signal transducer and activator of transcription 3 (STAT3) factor and nuclear factor-kB (NF-kB). Barb, D., Williams, C J., Neuwirth, A K., Mantzoros, C S. (2007) Am J Clin Nutr 86:s858-66. Miyazaki, T., Bub, J D., Uzuki, M., Iwamoto, Y. (2005) Biochem Biophys Res Commun 333:79-87. Targeted disruption experiments suggest that AdipoR1 signals mainly through AMPK, while AdipoR2 through PPARα pathways. Yamauchi, T., Nio, Y., Maki, T., Kobayashi, M., Takazawa, T., Iwabu, M. et al. (2007). Nat Med 13:332-9.
Interestingly, adiponectin may exert its biological activity indirectly, through selective sequestration of different growth factors (e.g., basic fibroblast growth factor, platelet-derived growth factor BB, heparin-binding epidermal growth factor) and inhibition of their normal receptor binding. These interactions involve specific oligomeric forms of adiponectin. Barb, D., Williams, C J., Neuwirth, A K., Mantzoros, C S. (2007) Am J Clin Nutr 86:s858-66. Wang et al. (2005) J Biol Chem 280:18341-7.
Adiponectin and Breast Cancer.
Adiponectin is thought to counteract the carcinogenic effects of fat-derived factors, including leptin. Cleary M P., Ray, A., Rogozina, O P., Dogan, S., Grossmann, M E. (2009) Front Biosci (Schol Ed) 1:329-57. Cleary, M P., Grossmann, M E., Ray, A., (2010) Vet Pathol 47:202-13. Jarde, T., Caldefie-chezet, F., Goncalves-Mendes, N., Mishellany, F., Buechler, C., Penault-Llorca, F. et al. (2009) Endocr Relat Cancer 16:1197-210. Several epidemiological studies found an inverse relation between adiponectin levels and breast cancer risk. Barb, D., Williams, C J., Neuwirth, A K., Mantzoros, C S. (2007) Am J Clin Nutr 86:s858-66. Miyoshi, Y., Funahashi, T., Kihara, S., Taguchi, T., Tamaki, Y., Matsuzawa, Y. et al. (2003) Clin Cancer Res 9:5699-704. Mantzoros, C., Petridou, E., Dessypris, N., Chavelas, C., Dalamaga, M., Alexe D M. et al. (2004) J Clin Endocrinol Metab 89:1102-7. Chen, D C., Chung, Y F., Yeh, Y T., Chaung, H C., Kuo, F C., Fu, O Y. et al. (2006) Cancer Lett 237:109-14. In breast cancer patients, adiponectin levels and the adiponectin:leptin ratio are reduced relative to that found in control women. Cleary M P., Ray, A., Rogozina, O P., Dogan, S., Grossmann, M E. (2009) Front Biosci (Schol Ed) 1:329-57. Cleary, M P., Grossmann, M E., Ray, A., (2010) Vet Pathol 47:202-13. Chen, D C., Chung, Y F., Yeh, Y T., Chaung, H C., Kuo, F C., Fu, O Y. et al. (2006) Cancer Lett 237:109-14. Moreover, patients with low adiponectin levels have more aggressive tumors and higher frequency of lymph node metastasis. Schaffler, A., Scholmerich, J., Buechler, C. (2007) Nat Clin Pract Endocrinol Metab 3:345-54. Hou, W K., Xu, Y X., Yu, T., Zhang, L., Zhang, W W., Fu, C L. et al. (2007) Chin Med J (Engl) 120:1592-6.
In vitro studies have confirmed the anti-neoplastic role of adiponectin. The hormone reduces proliferation in MCF7, MDA-MB-231, and T47D breast cancer cell lines, although some discrepancies regarding the response of individual cell lines were noted by different investigators. Dieudonne, M N., Bussiere, M., Dos Santos, E., Leneveu, M C., Giudicelli, Y., Pecquery, R. (2006) Biochem Biophys Res Commun 345:271-9. Kang, J H., Lee, Y Y., Yu, B Y., Yang, B S., Cho, K H., Yoon, D K. et al. (2005) Arch Pharm Res 28:1263-9. Korner, A., Pazaitou-Panayiotou, K., Kelesidis, T., Kelesidis, I. Williams, C J., Kaprara, A. et al. (2007) J Clin Endocrinol Metab 92:1041-8. In MCF cells, the inhibitory effect is associated with increased activation of AMPK and reduced MAPK signaling. Dieudonne, M N., Bussiere, M., Dos Santos, E., Leneveu, M C., Giudicelli, Y., Pecquery, R. (2006) Biochem Biophys Res Commun 345:271-9. In MDA-MB-231 cells, adiponectin blocks the Akt kinase and glycogen synthase kinase/β-catenin pathway. Wang, Y., Lam, J B., Lam, K S., Liu, J. Lam, M C., Hoo, R L. et al. (2006) Cancer Res 66:11462-70. Interestingly, adiponectin can also inhibit breast cancer cell migration and invasion. Taliaferro-Smith, L., Nagalingam, A., Zhong, D. Zhu, W. Saxena, N K., Sharma, D. (2009) Oncogene 28:2621-33. In animal models, adiponectin suppresses the growth of T47D and MDA-MB-231 xenografts, and in some experiments reduces tumor neoangiogenesis. Cleary, M P., Grossmann, M E., Ray, A., (2010) Vet Pathol 47:202-13. Wang, Y., Lam, J B., Lam, K S., Liu, J. Lam, M C., Hoo, R L. et al. (2006) Cancer Res 66:11462-70. Saxena, N K., Sharma, D. (2010) Cell Adh Migr 4(3):258-62. AdipoR1 and AdipoR2 have been detected in human breast cancer specimens, but at present, there is no consensus regarding their association with clinicopathological parameters. Pfeiler, G., Treeck, O., Wenzel, G., Goerse, R., Hartmann, A., Schmitz, G. et al. (2009) Maturitas 63:253-6. Tahakata, C., Miyoshi, Y., Irahara, N., Taguchi, T., Tamaki, Y., Noguchi, S. (2007) Cancer Lett 250:229-36. One study suggested that AdipoR1 is expressed at higher levels in pre-invasive breast cancer (DCIS) than in invasive lesions. Pfeiler, G., Hudelist, G., Wulfing, P. Mattsson, B., Konigsberg, R., Kubista, E. et al. (2010) Gynecol Oncol 117:134-8. Between the two receptor types, AdipoR1 appears to play a more definite role in breast cancer as adiponectin-dependent antiproliferative effects are abolished by siRNA knockdown of AdipoR1; cell lines expressing AdipoR2, but lacking AdipoR1 do not respond to adiponectin with growth inhibition. Nakayama, S., Miyoshi, Y. Ishihara, H., Noguchi, S. (2008) Breast Cancer Res Treat 112:405-10. Grossmann, M E., Nkhata, K J., Mizuno, N K., Ray, A., Cleary, M P. (2008) Br J Cancer 98:370-9.
Numerous epidemiological and experimental studies provided evidence linking obesity with the increased risk of development of different malignancies, including breast, colorectal, prostate and endometrial cancers. Maiti B, et al. Breast Cancer Res Treat 2010, 121(2):479-83, Vona-Davis L, et al. Obes Rev 2007, 8(5):395-408, Calle E E and Thun M J Oncogene 2004, 23(38):6365-6378, Pischon T, et al. Proc Nutr Soc 2008, 67(2):128-145. In addition, a calorie-rich diet has been shown to induce inflammatory responses in microglia cells, which potentially can promote development of brain neoplasms. Velloso L A, Arq Bras Endocrinol Metabol 2009, 53(2):151-158, Reynes G et al. J Neurooncol 2020, 102(1):35-41.
In obese individuals, especially in those with high visceral fat content, adiponectin levels are low. Brochu-Gaudreau K, et al. Endocrine 2010, 37(1):11-32. Many epidemiological studies demonstrated a link between low adiponectin and elevated risk of cancer development or presence of more aggressive neoplasms. Chen X and Wang Y, Adiponectin and breast cancer, Med Oncol 2010, 28(4):1288-1295, Brochu-Gaudreau K, et al. Endocrine 2010, 37(1):11-32, Pfeiler G et al., Maturitas 2009, 63(3):253-256. The mechanism underlying adiponectin signaling and cancer prevention is not clear, but it could involve induction of intracellular metabolic changes similar to those produced by calorie restriction, i.e., activation of intracellular signals such as AMPK and inhibition of growth and survival pathways Brochu-Gaudreau K, et al. Endocrine 2010, 37(1):11-32, Pfeiler G et al., Maturitas 2009, 63(3):253-256. Thus, pharmacological activation of adiponectin signaling in obese individuals that are refractory to lifestyle modifications could help to restore beneficial pathways normally controlled by this hormone.
Several studies support the notion that full length adiponectin or the globular domain of adiponectin (gAd) can produce various effects on cancer cells. In many different cancer cell lines (breast MCF-7, MDA-MB-231, T47D; colorectal HT-29, CaCO2, SW480; prostate PC3) adiponectin activated AMPK. Kornet A, et al. J Clin Endocrinol Metab 2007, 92(3):1041-1048, Dieudonne M N, et al. Biochem Biophys Res Commun 2006, 345(1):271-279, Williams C J et al. Endocr Relat Cancer 2008, 15(1):289-299, Zakikhani M, et al. Cancer Prev Res (Phila) 2008, 1(5):369-375. Adiponectin either reduced or did not affect ERK1/2 in MCF-7 or MDA-MB-231 cells, but stimulated the pathway in some colorectal cancer cell lines. Grossmann M E et al, Br J Cancer 2008, 98(2):370-379, Dieudonne M N, et al. Biochem Biophys Res Commun 2006, 345(1):271-279, Williams C J et al. Endocr Relat Cancer 2008, 15(1):289-299. Akt was inhibited by adiponectin in MDA-MB-231 breast cancer cells, but activated in prostate cancer cells LNCaP. Kim K Y et al. Cancer Res 2009, 69(9):4018-4026, Barb D et al., Endocr Relat Cancer 2007, 14(4):995-1005. Moderate STAT3 stimulation by adiponectin was noted in MDA-MB-231 cells, while the transcription factor was inhibited in DU145 prostate cancer cells. Grossmann M E et al, Br J Cancer 2008, 98(2):370-379, Miyazaki T et al., Biochem Biophys Res Commun 2005, 333(1):79-87.
Although full size adiponectin or its globular domain have been shown to exhibit positive effects on various cells and tissues, the development of this cytokine into an acceptable pro-drug is pharmacologically and economically disadvantageous. Instead, small peptides or peptidomimetics based on the minimal adiponectin/adiponectin receptor-activating domain should constitute appropriate leads for drug development. Such adiponectin receptor agonists should be equipped with enhanced specificity, low toxicity, high stability, superior bioavailability parameters, and low production costs. The present invention addresses and meets these needs.